Former champion Shaun Murphy suffered a shock 6-3 defeat to China's world number 124 Chen Feilong in the first round of the UK Championship in York.
Murphy, who won the tournament in 2008 and was also runner-up in 2012 and 2017, surrendered a 3-1 lead in the match as his poor start to the season continued.
Murphy said: "I didn't see that coming because I have been practising so hard, and my preparations for this event have been fantastic.
"I have had a terrible season so far but that has left me a lot of time to practice and I feel my game is in such good shape - but I'm still waiting for that to come through."
Another former winner, Jimmy White, saw his hopes of a run in the tournament brought to an end in a 6-3 defeat to Thailand's Thepchaiya Un-Nooh.
White, 56, now ranked 77 in the world, put up an encouraging performance against Un-Nooh, scoring three breaks over 50 including a 97 to temporarily threaten a comeback before his opponent finished the job.
Three-times UK champion John Higgins suffered a mighty scare before edging into round two with a 6-5 win over Dechawat Poomjaeng.
Higgins struggled desperately as the Thai, who dropped off the main tour last year, battled back from 5-3 down to force a decider.
But at gone half past midnight, Higgins seized on a second chance after a missed yellow to rack up a 60 break and wrap up a wholly unconvincing win.
Higgins said: "It's the way I've been playing all year - it's no surprise to me how I played out there and I'm really lucky to get through."
World number 12 Ryan Day was another surprise loser as he went down 6-2 to world number 121 Joe O'Connor, while Mark Allen won by the same scoreline, booking his place in the next round with victory over Basem Eltahhan.
Wednesday November 28 results
Morning session (0930 GMT)
- Marco Fu 6-0 Hammad Miah
- Jimmy Robertson 6-4 Jordan Brown
- Li Hang 6-3 Lee Walker
- Andrew Higginson 6-2 Nigel Bond
- Mark Joyce 6-3 Niu Zhuang
- Liam Highfield 6-4 Robin Hull
- Stuart Bingham 6-0 James Wattana
- Anthony Hamilton 1-6 Rod Lawler
Afternoon session (1430 GMT)
- Shaun Murphy 3-6 Chen Feilong
- Ryan Day 2-6 Joe O'Connor
- Joe Perry 6-0 John J Astley
- Tom Ford 6-5 Craig Steadman
- Alan McManus 6-1 Alexander Ursenbacher
- Akani Songsermsawad 6-5 Eden Sharav
- Michael White 5-6 Joe Swail
- Graeme Dott 6-2 Oliver Lines
Evening session (1930 GMT)
- John Higgins 6-5 Dechawat Poomjaeng
- David Gilbert 6-3 Ashley Carty
- Stuart Carrington 1-6 Paul S Davison
- Mike Dunn 5-4 Allan Taylor
- Gary Wilson 6-4 Billy Joe Castle
- Mark Allen 6-2 Basem Eltahhan
- Martin Gould 6-1 Harvey Chandler
- Thepchaiya Un-Nooh 6-3 Jimmy White